1. Field of the Invention
This invention relates to a vacuum fixing device for parts, and more particularly to an effective technique applied to a vacuum fixing device which sucks and fixes a part in a vacuum or reduced pressure state, wherein a variety of parts can be sucked and fixed successively by simply switching a small vacuum pad over to a large vacuum pad or vice versa.
2. Related Art Statement
For example, a vacuum fixing device for sucking and fixing a part is used in a parts transfer system in an interlocking relation to a chip mounter which mounts an electronic part such as a semiconductor device onto a printed circuit board, in such a manner that the electronic parts housed in a tray or the like are taken out one by one at a loading position, sucked and fixed by a vacuum pad of the vacuum fixing device, transferred to a predetermined releasing position through a transfer path, and thereafter, mounted onto the printed circuit board by a chip mounter.
Among the vacuum fixing devices as described above, there are one In which a small vacuum pad and a large vacuum pad, which are formed as separate bodies having different diameters from each other, can be exchanged for each other. Another type of device employs two axes system in which a small vacuum pad and a large vacuum pad are mounted on their axes respectively and can be switched over to each other. In both types of devices, for fixing a part in a vacuum or reduced pressure state by a vacuum pad, the small vacuum pad or the large vacuum pad is selected according to the size of the part to be fixed.
However, according to the above-described conventional technique, for example, in the system wherein the small vacuum pad and the large vacuum pad which are formed as separate bodies are exchanged, such problems are presented that the exchange by a worker is necessary in accordance with a change of the size of a part to be fixed, and, particularly, when the vacuum fixing device is used in an interlocking relation to another apparatus, the exchange may be impracticable.
Furthermore, in the case where two axes system is employed to switch over the small vacuum pad to the large vacuum pad or vice versa, because the positions of the two axes are different from each other, the positions of loading and releasing a part are different depending on whether the small vacuum pad or the large vacuum pad is used, whereby control of switchover or the like becomes difficult, and further, the operation time is lengthened.